Welcome to ShootUp Peter – I think it all depends on what your specific requirements are, so I’d definintely ask to have a play with all 3 and see which you like best.
And because I wrote it, I am obliged to plug my review of pumps available in 2011 which covers all your choices (it talks about the Paradigm Veo but the Paradigm 515 is it’s predecesor and there isn’t a huge world of difference between them). http://www.shootuporputup.co.uk/2011/01/picking-a-pump-in-2011/