I'll throw in my 2 cents, since I've listened to many of the speakers mentioned in this thread, and done level match A/B comparisons between several of them.
My favorite $300ish options (based on US pricing/availability and excluding used speakers)...
1. Energy RC-10 - my overall favorite in this price range, even if slightly overemphasized in the upper bass/lower mids and a touch laid back in the upper mids/lower treble, the overall sound just works really well for my ears
2. Wharfedale Evo2-8 - probably my favorite mids/highs of the speakers in my list; wide soundstage; the big strike against them for me was the lack of bass... but crossed over to a good sub (in the right placement) around 110-120Hz, these can really shine
3. Wharfedale Diamond 10.1 - very nice, balanced and nonfatiguing; but a little darker/less lively than the RC-10 to my ears; strong bass (maybe a bit too much)
4. NHT Absolute Zero - within their limitations, very neutral, if slightly "analytical"; clean/detailed midrange, without the edginess I found with the S30, as long as they're not pushed too hard; lacks the bass/dynamics/scale of the others... a nice little speaker provided you understand the limitations
5. Cambridge S-30 - a little edgy/emphasized in the upper mids/lower treble to my ears, but overall still nicely balanced with impressive/quality bass for it's size (I haven't heard them, but it appears the Mordaunt Carnival 2 would be similar)
1. HTD Level 2 - Bearing in mind I heard these over 4 years ago... I felt the AV123 X-LS was a better speaker, and I felt the RC-10 was a noticeable step up over the X-LS
2. Ascend HTM-200SE - I ran level matched A/B comparisons with these against the Energy RC-Mini Centers and PSB Image B4, and felt they were comparable in overall performance... with none offering the level of performance of those listed above.
All just my opinions.... Your mileage may vary.