Virus TI - lovely feeling keyboard
Radias - *Probably* a really horrible keyboard - I would say get a rack version, but the extra for the keyboard is minimal...
Beyond that - I cant relate to buying a synth on just on features... Buying a synth on that basis can land you with a real serious risk of ending with something that has every feature you could wish for, and yet you just plain dont get on with its sound, and so you end up not using it much, and its a waste of money basically (unless bought second hand so u can flog it for the same price). Sometimes a sound you dont likie slowly grows on you (I didnt like the souds of Nords, but slowly its growing...)
As a TI owner and having heard a bunch of demos of the Radias, it seems they are both more than different enough for some people so end up with both (actually I know of someone who does allready have both).
I do quite like what the Radias seems to offer sound wise - if I didnt have some of the gear I allready have, then I might seriously consider getting one if after having a play with one if I liked it - a Virus TI would still be a first choice and a Radias would be a companion to the TI. As it is - I feel no deparation and maybe buy the time Im looking for a change of synth - the price might have dropped
Just to throw in something random - you could buy an Alesis Fusion synth workstation for considerably less if its features you are after. I have been vaguely thinking of dumping my Motif ES rack for an 8HD (88 key weighted version - still slighly cheaper than the radias, it has 32 track sequencers, 8 track audio recorder, 4 synth engines, incl VA, FM sampling, and physical modelling). It seems to have had a ropey start (OS bugs, crappy initial set of sounds etc) but Alesis have just massively reduced the price on it, and there some good sound sets for it and its quite easy to program and serves as a useful sampler. For me it would be more of a tool kit for sampling, sequencing etc, but I do quite like its FM capability and the stock sound presets are useful now as well.