never heard that onkyo, but many say they are noted more for reception than for sonics.  someone on the yahoo tuna forum posted about this - fantastic sound for small dinero:
http://www.audiogon.com/cgi-bin/cls.pl?misctunr&1243561125&/JVC-FX-1100BK-tuner
Being a ham operator and communications engineer, I guess I am more drawn to the "DX machine" kind of tuner!  The 4087 is a little brother to the 9090.  I had a heavily modified (by Ed Hanlon) Yamaha T-85 that was a real killer-- sounded pretty good too! Ed replaced a lot of caps in addition to installing a full line up of filters.
the jvc is no sluch in the reception department, imo.  the yamaha t-85 is supposed to be wery nice; i have only owned a yamaha t-2 (another tandberg 3001a alternative).  (btw - the only difference between a 3001 and a 3001a is the color - 3001 is silver, 3001a is black.)  re: ed hanlon, he subs out all his work; i would suggest in the future going directly to a tech; why pay a middle-man?  and a neurotic manic-depressive one at that!  

I think you will pay a premium for the Sansui's.  One indirect consequence of sites like TIC is that certain highly rated tuners have really taken off on the used market.  I think what Doug is suggesting is a good strategy-- get your feet wet without spending too much by looking for tuners like the JVC FX1100BK.  You can sometimes find tuners like these at yard sales for $10 or $20!  If you are happy with them you can then take the plunge into Sansui, Kenwood, etc...
tu919's are not cheap - plan on ~$600 or so.  but, $300 is top dollar for a tu717; careful shopping can often find them for less - sometimes substantially so.  and, a tu517 is the same tuna, sans record calibrate feature - these usually also sell for less...  and, yard sales/craigslist is also a way to find tunas cheap, for sure.  the only reason i bought my second fx1100bk, after i sold my first, is cuz i saw it on c/l for $20, i offered the guy $10, he accepted, and i picked it up on my way home from work.  i yust couldn't help myself!   

doug s.