Yes and no. UA has a very liberal 24-hour (not same-day, BIG difference) free flight change policy, which can be advantageous to you. UA also provides 1 free drink + 1 free menu item for GS/1K seated in Y, just like AA does for EXP, so yes on those. UA's menu options are better than AA's as well, IMO. But you probably had better upgrade chances as PLAT than as 1K at UA, so no on that.

I am UA 1MM, so lifetime *G. This is my 3rd year as EXP. Part of my reason for coming over to AA was the changes made to the MP program, and part of it was AA's better flights at LAX (except Asia/Greater China). It's been an extremely liberating experience to step away from UA after all those years, especially considering that I can now enjoy elite benefits on two alliances. I now divide my flying between AA and UA ~66%/33%. Good luck to you.