my current fave-sounding tuna is a stephen sank modded harmon-kardon citation-18. it has eeked out my completely refurb'd tandberg 3001a, as well as my long-time fave onix bwd-1. i was turned on to it by a tuna-freak, who had many tunas in his system, before settling on the h/k 18. this included, but was not limited to, tandberg 3001a, sequerra fm reference, mcintosh mr78, marantz 10b.
go here for info about *many* relatively inexpensive vintage tuna that will smoke anything presently awailable new up to $2500, & will equal anything made at anytime, for any price:
http://fmtunerinfo.com/ for related discussion group:
http://groups.yahoo.com/group/FMtuners/ and, ya will also find, like other things audio, personal taste comes into play. for example, one of the tuna gurus of the list has been doing his own li'l "shootout". he's up to having reviewed/compared 31 different "species", and the sequerra model 1 doesn't even make it into the top half...
for a cheap/good new tuna (i'd still go the vintage route, myself), i don't tink ya could do any better than getting a modded one from ed hanlon, of antenna performance specialties. i haven't heard it, but i have experience w/his antennae, and folk who have used him for tuna work have had unanimous praise. also, a good antenna is mandatory for true a'phile fm sound (as well as quality signal from stations, someting getting rarer & rarer these days.

) ed has killer antennae; for less $$$, the winegard hd6065 is also killer...
http://antennaperformance.com/regards,
doug s., tuna addict