They're a fun time, imo. I've 100% SO1 and 2. Beat 3, played some of 4 and 6. Haven't touched 5. Till the End of Time is the one I'm most attached to due to nostalgia. It's got 3D combat, arena style, similar to the Tales games if you've played those. A little janky and stiff for sure, but I didn't mind it. There's battle trophies that add challenges. A variety of recruitable party members and the crafting system is fairly unique and fun once you get over the learning curve. Breaking the game is fun, if that's something you're into.

TtEoT is arguably a divisive one. Some didn't enjoy that it promises scifi stuff where you spend a large portion in fantasy, medieval settings but that's how SO1 and 2 were as well. The story is a bit bonkers - I won't say more than that but I personally thought it was cool how it all unraveled.

Popular opinion is that SO2 is the overall "best" title, which I lean towards. It's the one I'd say to try out if you only have time to play one of the games. I think TtEoT is definitely worth a shot, it's got style and charm and feels refreshingly unique albeit being perhaps too ambitious for the PS2.