Yeah, kinda. The game has no upgrades on next-gen (because R* hates us) so it doesn't look any different on Series X/PS5 vs. XBONE/PS4. It would run better, especially in 4K, but the graphics won't really change. It's definitely better than playing it on XBONE/PS4 but don't get your expectations too high.

Depends on what games you play, which console is more available in your area (I can't believe this is still an issue), and if you're interested in multiplayer with friends, what consoles the people you want to play with have.