I guess it all boils down to what defines a "mid range" HF radio. Is it price or performance? Both are easy to define but unlike conventional wisdom, the two don't track linearly. There are radios priced at the high end whose performance in some areas is mid-grade. For example, there has been a lot of talk about the FT-5000 lately on the Elecraft mailing list and while reactions to the latest review of it in QST were positive,
it was pointed out that the transmitted phase noise is only -130 dBc/Hz from 10
kHz to 1 MHz. As the referenced poster argued, when feeding an amplifier at legal limit, the transmitted phase noise will be S4 or so in
any receiver within a
mile or so of that station! By his calculations one may need to be at least 6 miles away before the transmitted phase noise drops below the band noise. In my opinion, that is unforgivable in 2010. Especially from a radio that is touted as being top of the line or thereabouts.
The above example is not unusual, sadly enough. I know that we spend most of our time comparing features and receiver specs, but our transmitters impact everyone around us when we transmit. There will be those who argue that such rigs meets Part 97 specs but that is the bare minimum we should strive for.
So, what do we do? The easiest is to compare specs and shop accordingly.
ARRL maintains an archive of product reviews that have appeared in QST over the years. These documents are an invaluable resource as they are really the only documented tests most radios ever receive.
All that said, what's my recommendation? Of course it would be the K3. Yes, it seems pricey fully optioned, but I think the performance and continuing improvement and addition of features make it an incredible value and its friendly to our neighbors on the bands. Various ops have reported operating two K3s on the same band simultaneously without knowing the other was there until within about 10 kHz (I have no experience in that regard).
So if we compare by price and consider that $5 to $10k roughly defines the "high end" offerings and $1500 and lower defines the "low end", we can fit a lot of radios comfortably into the "mid range". As optioned, my K3 with 100 Watt PA, 1 PPM TCXO, and additional 2.1 kHz and 500 and 200 Hz filters came in at just under $2400 (biggest one-time purchase of my ham radio career) which is well under the mid range mid-price point of $3250. Adding the internal tuner is another $300 which still is well below the mid range middle price point. Of course that is still about $900 above the TS-590S mentioned earlier which makes a difference to a strained budget, but the K3 offers up to five filters in each receiver when the optional second receiver is added. There are more features and ways to use this radio that I've yet to explore but I have a rig that ranks near the top in all around performance for a lower mid-range price. That is an amazing value to me for a "mid range" radio.