Who can the OP learn the most from? Well, for the most part, great as he was, Entwistle soloed through the Who's canon, being pretty much the lead player in the band, while Townshend held down the rhythm (probably the reason most folks don't like Pino with the Who, he's playing rhythm too). Squire, on the other hand, was mostly supporting the guitar and keyboards while they went off on one. So, if the OP is in a band where he can solo all the time, JE is the one to pay more attention to. However, if his role is more traditional, CS is a better example. IMO listen to both (they were both fantastic musicians, ahead of their time and just monster technicians) and just take what works for you.