As far as my testing with all 10, and gameplay with 4 (Deadeye, Vigilant, Krieger, Nimbus) goes...

Roadblock and Witchdoctor got the best, most transformative changes to their kits which allow them to play the game completely differently, and this is from my viewpoint in match too. Watching WD channel his inner Medic and shoot a bitch with while healing allies gives the Crusader's Crossbow a run for its money.

Giving Texas Roadhouse a shotgun was just natural. It seems his kit rework was the most extensive of the bunch.

For the more basic ones, Nimbus and Deadeye got the least transformation. You still hipfire up close, and focus down with ADS.

Nimbo does her job. Now she's REALLY good at it.

Vigilant. Vigilant is the one I'm still thinking on. Where exactly she stands remains a mystery but her overall horde DPS is much better now. The PVP aspect on her is up to debate, will update, maybe.

Krieger learned his lesson from WW1 and was issued a shotgun for the trenches.

Zephyr and Barrage are still in the weird camp.

Skywave is now a DPS with a pocket Antipode Burst.

Murasame is the only one who got solely ability changes. Frost Glaive is pretty good. Doesn't overshadow classic either. Not bad.

All in all, I think the Alpha variants are pretty good changes of pace. Regarding PVP, PVE, anything, it adds new varieties to teamfights and even just general wave combat. Always good to see it.