As far as twist-shifter goes SRAM is the best of the bunch, they have the longest "griptube" of them all. But twistshifters are not a good choice for a recumbent I never liked mine so a couple of years ago I swapped them for barend shifters, one of the best choises I made. I absolutely love my barens shifter, smooth shifting and you can see at a glance which position is in. Of course I had to remove my rearview mirrors but they now resides on the helping handles which is a much better position for them.
The only 8-position barend shifters I could find was Shimano Ultegra and my rear derailleur is a SRAM X-9. According to all experts it wouldn't work with the index-setting, but as stubborn as I am I opted for the index-setting when I went for my test-run. No problem! all positions but one (seldom used) works perfectly. I actually have an Ultegra rear derailleur in my "spares-cache" but I haven't mustered enough ambition to mount it yet.