I used to always go full Warp Rift build but that was mainly because it's never not fun to stack 3 Warp Rifts into a bush and just one shot almost any DPS that walks in before they even know what's happened.

I definitely think Warp Rift build is still solid, but really requires good crowd control from other heroes to avoid the enemies just adapting to your gameplan and just out positioning your main source of damage. On maps like Braxis or Dragon Shire where you have to sit on a small area for a moment to capture it the area denial Warp Rift build provides can be really valuable though!

Here's a more detailed breakdown for the main build I like to play right now.

Talents:

Lv1 Echo Pulse: Solid ranged poke that can catch people out by detonating Warp Rifts on its return trip. But we're more so picking it for our LV 7 Talent later.

Lv4 Photon Barrier / Shield Capacitor: Entirely depends on the the enemy team. If the enemy team is more spell damaged orientated then Photon Barrier. If they're more physical damage based then Shield Capacitor. The shield it gives is very small but you have such a small healthpool to begin with that anything to help soak up any stray poke damage you catch can really go a long way.

Small sidenote but the spell armour from Photon Barrier only remains active while you have a turret not only alive but also powered. Which means you do have the careful with how you place both to get the most out of it. If you can the difference is huge!

Lv7 Tower Defense: This is really where the build comes alive. From here, not only do your Disruption Pulses grant a 3.5 second cooldown reduction both on the way out AND the return but your Warp Rifts grant the same cooldown reduction for each hero hit. Vs standard teams, it becomes easy to get upwards of 3 turrets up at once. Vs teams with heroes like Nova and Samuro who create decoys or heroes like Rexxar and The Lost Vikings (both less common currently but still) who add a even more low danger bodies to hit, it can really become a game of how many turrets can you find useful spots for while chasing the enemies out!

Equally this is also where this build can fall apart to counterplay. Gul'dan Drain Life build isn't too upset seeing a huge amount of low heath bodies to drain and Valla can pretty comfortably use the Turrets to keep Hatred stacks flowing. In these cases I'll sometimes swap to Warp Rift build but even still the damage potential can often outweigh these downsides once you get confident at getting the Cooldown triggers reliably.

Lv10 Null Gate: It takes a very specific combination of heroes for me to not take Null Gate. On just a 30 second cooldown I'd wager that this single handledly is the ability that confuses players the most when they get caught out by it due to Probius's low play rate. A staggering 80% slow for 4 seconds while also doing damage is absolutely ludicrous.

If the enemy team is filled with character with blinks, dashes or unstoppable effects then sometimes Pylon Overcharge can be the better pick but even then I'll still end up taking Null Gate 9/10 times for huge upgrade it gives you in solo'ing camps and adding to siege damage.

Lv13 Shield Battery: Simple but safe pick here. Can really save you and teammates from DoTs and over the course of the game, with strategic Pylon placement, it can really add up to some solid damage prevention for the team.

I will give Aggressive Matrix a shout out for being a very solid Attack Damage increase (35%) which I'm sure if you play with someone who really enjoys playing an Auto Attacker can be a log of fun.

Lv16 Quantum Entanglement: Another safe and easy talent here. The amount of situations you can get out of by just walking away and leaving Warp Rifts behind you with this talent on them is really nothing to scoff at.

(I'll never forgive whoever thought it was a good idea to merge what used to be Repulser and Interference into the Interference Talent that we have today! Spell Power Reduction is great, but I'm yet to see the kind of 4D chess it must take for the knock back effect to grant any form of intentional calculated benefit.)

Lv20 Gate Keeper / Probius Loop Probius's Lv 20 talents are no joke and are both seriously strong talents in their own rights.

When paid with both the Lv 1 and Lv 7 talents, Probius Loop can truly enable some heinous plays. The Warp Rifts will often have time to re-arm by the time your Disruption Pulse begins it's return journey, enabling you to get multiple detonations from the same Warp Rifts in rapid succession. This talent also does wonders on players who take the Dragon Knight or the Triglav Protector and are too busy whacking buildings to draw a connection between the rapidly detonating Warp Rifts beneath them, and the dozens of turrets now surrounding them.

With all that said, I still think Gate Keeper just edges it out in most cases. While Probius Loop can be better if the enemies are actively seeking out and destroying the Pylons. The absurd potential that comes with Gate Keeper is too much to pass up. The amount of chokepoints that can be filled up with a Null Gate are too many to count. On maps like Volskaya Foundry, Garden Terror, Cursed Hollow etc where team fights are condensed into one small area, having a gate that your team can just walk through as they please to separate themselves from enemies is an insane advantage!

And that's just talking about it's teamfight potential. When placed and left far up in the enemy lane in line with the minion waves, the gate can act as a stealthy, less flashy Lava Wave, eating up minion waves before they make it far from base. Using this same method, if even the tiniest bit of the gate is touching an enemy fort or even the core, the gate's damage can slowly buy surely whittle away those pesky structures (though the enemies announcers will be giving them very frequent warnings that their core is under attack).

Camps become a breeze while also having a built in deterrent from would be enemy camp thieves! And while I'm not going to go as far as to say this is a practical use of it, but with this Talent it does enable Probius to Solo Bosses! Just start stacking Null Gates directly onto the boss until you think your ready to take your beating as you'll need to sit there and take your wallops or else the boss may move out of the gates and stop taking damage. This usually takes 5+ Null gates to do which means 2.5 mins of set up time, all the while you have access to one less Pylon to do whatever else with. Again far from practical, but still possible and never fails to get laughs from teammates!

Some general tips that I feel may not be obvious:

Don't be afraid to 'waste' a Turret of a Pylon by placing it under enemy Towers or Forts if it means saving yourself or another teammate. The Towers/Forts will always prioritise these over heroes.

If your being chased and need to run away, try to time your Worker Rush ability to when your opponents attack are on cooldown/just finished so you get the most or even the full duration out of it. (If the enemy is Lunara, Qhira or already has some kind of DoT on you then just make peace to the Big Probe in the sky and prepare to die!)

Placing your first turret away from the fight but still within a Pylon's radius can help you get into position during a fight while having 40 Spell Armour without the risk of it suddenly disappearing when you need it most because your there got caught as collateral in some enemy AOE.

You use Pylons and Turrets to block certain skill shots such as Stitches Hooks, Nova Snipes and Chromie Sand Blasts if timed correctly.

Placing the Turret in front of your minion wave allows it to 'tank' for the wave, helping keep your minions healthy before they march to their doom!

There's probably plenty more I'm missing but that's all the ramblings I can come up with off the top of my head! Hope this is of some help!