I have two decks.
One is Technics 1506 which has been modified both mechanically and electronically by Bottlehead (5 years old). All the electronics are bypassed (including the meters!) to a Bottlehead prepro which has a switch to change from NAB to CCIR EQ. When I bought my machine (toward the beginning of the Tape Project) there were really no competitive after market prepros that I knew about. Charles King, Doshi, Havilland? all came later. Bottlehead did all of the work including providing the deck. They disabled the record electronics and replaced the record and erase heads with dummies. It also has a very cool remote control so I can play, stop, ff, rewind all from my listening chair.
The second is an Otari MX-5050 BIII (not II) that I bought used, but in quite fine condition. As Myles stated, there is a switch in the back to change EQ. It also has balanced in and outputs only, with pin 3 hot - the Japanese convention, most balanced electronics are pin 2 hot. The BIII can take the standard reel hubs, while the BII is a bit of a pain to mount and dismount big reels. The mechanics were in very good shape and it came with a 2 track record and playback. I bought a replacement head block which also has a 4 track playback only. John French relapped the heads. If I need to record 2 track, then I use the Otari.
I never heard the Technics electronics so I cannot comment on those, but my Otari definitely has good enough electronics to be a starter deck for people who want to play Tape Project and the other newly recorded 15ips, 2 track tapes that are becoming more common. You can upgrade the electronics as your budget allows.
The Otaris are quite easy to get and don't have the cache of the Technics (nor do they look as nice - no fancy closed loop capstan). But they are quite sturdy and I got mine locally for less than 10% of the price I paid for the Bottlehead Technics. I saw the ad for it on the internet, but drove down with a couple of test tapes to see it and actually play it before I bought it. Many (most?) of the used tape recorders are really beaten up (the guy who sold the Otari to me had bought out the inventory of a radio station that was closing.) I think he had 4 or 5 tape recorders including a 5050 BII which was well worn. I could have bought it for $150 or so. I stuck with the BIII which was less than $500.
Not sure whether Otari is still making the 5050, but it was until a few years ago. I remember a price of about $5000, but I could be wrong.
Larry