I can see Marvin Rees getting re-elected as the city remained very strong Labour in the General Election and the Conservatives did have a decline in their vote share (along with Labour before I get accused of bias).
I do wonder who will finish second - there's quite a Green presence on the local council there and they did quite well in Bristol West so they can't be discounted. The Tories, again have a lot of support in areas like Westbury-on-Trym, Bishopworth, Henbury and do have some presence on the council so there another one who could tussle for silver. If they put up Mark Weston again, I'd rule them out totally. The Lib Dems nowhere to be seen, despite doing OK in the GE.
Be interesting if any big name Indies stand as that could dent the vote for everyone.