Hi not so long back I was in the same position, it depends on how much you want to spend but here's what I looked at:
New Rollei GX is about £2,500 at Robert White.
A good secondhand F either Xenotar or Planar will be around £500 for a good model recently serviced (FFordes have a couple)
Or look for a good user model for about £200 and have it serviced about £80-120 for a good service.
What did I do?
I bought a Rolleiflex T which has a Tessar F3,5 for £100 on ebay then sent it to Brian Mickleboro for a service.
I write about it in my blog:
Rolleiflex T
Some consider the T inferior to the F models, but I like the Tessar and if you stop down to F8-11 you can tell the difference IMHO.
Just some food for thought.
Mark