I can't see Leeds working on its own. It is certainly big enough - supposedly the largest city in Europe to have no local rail system at all, although I would suggest that Liverpool is arguably bigger and that Merseyrail does not count - but I just don't think its layout would work. If you could run a combined system with Bradford, then go for it. Bristol is better because (a) there are clear primary routes into the centre which have only a few buses an hour, (b) it is well built in three directions, with only south being a problem, (c) it has a ready-made railway available in the Severn Beach Line, and (d) it would provide better connections between city centre and main station, which is not an issue in Leeds. Both could have hill issues though, and thus potentially long disatances between surface and platforms.
One that I think could work would be Brighton. Remove the local stations on the West Coastway between Worthing and Brighton itself, leaving only Shoreham and Hove, and then convert the Littlehampton and West Worthing terminators into a through Metro service which leaves NR metals at Worthing and runs into Worthing centre, before ultimately terminating at either Falmer or the Marina.