Jeez... this is a question with many variables involved, including your budget and personal preferences.

Here's a topic I once started that might give you a starter:
viewtopic.php?f=2&t=46413

Great info. That’s what I was looking for. I’ve gone through the painstaking process of lining all of my favorite rods and it’s worth the effort. Ironically, some of my newer $100 lines may never see the water again...

SA DT "Trout" lines for me.

I've become very fond of the 406 lines for glass & cane rods.
tt

I use Wulff TT floating lines based on a long ago recommendation from McFarland and they are excellent lines. Most of my fishing these days involves sink tip WF lines. Soft hackles a Teeney mini tip, streamers Rio, SA, and Wulff TT 25 ft tips. I only have one one full sink line, an SA. All do the job within my capabilities.

I use a single spey line Orvis Bank Shot on my Superfine 6wt it throws large bugs nicely

Quite fond of the Wulff TT's and Longbelly flylines, sunset Masterline and Chalkstreams, but really most lines work very well, some though a a bit of magic.

That covers it pretty well. In truth, neither my 'glass nor my carbon rods have ever cared what brand or taper line was used, the rod is mostly just a handle, so pick the line to match the fly and the job; floating lines for top water work and sinking lines for deep water, heavy lines for large flies and light lines for delicate presentation of midges and so forth.
If one looks at the taper profiles and weight distribution of each line it will probably indicate some manufacturers market the same line under several labels aimed at specific fish, differing only in box color and price.
Cut a DT in half and splice it to running line and it becomes a WF, cut 5-7' off the front of either and they become basic level lines.
Add a few inches to the tip or to the rear taper of any line and you can market it as some new line for $10 more.
Change the color of the dye and double the price and everybody will need the "new" "improved" line.
After several decades of every company touting how slick their lines were and how wonderful "slick" was/is, they suddenly found that rough/textured/sharkskin/etc could sell.
I'm not a good enough caster to appreciate the difference that ten grains of weight (spread over 30') or six inches of extra rear taper or ten more feet of running line makes. I do like slick. I can get about any front taper I want by changing leaders or leader design. By 1985 the lines had about as good of design as they do now, as far as I can tell. Plastic is still plastic and there is only so much manipulation that can be done with any material, marketing though has no limits.

I am partial to DTs and longer bellied WF lines. They are more honest and versatile. The specialty lines can be one trick ponies designed to mask operator shortcomings. For vintage rods that sometimes don't have the best guides or not enough guides, slickness is particularly important, that can be dealt with by keeping the line clean and well dressed. I tend to like SA and Cortland as brands.

I’ve got the Orvis Bankshot on my System 7, and I have Cortland Peach DT and Orvis Superfine WF lines for my Orvis SFG and Flea (bamboo) rods. Both work well, although I find I like the double taper more. My Abercrombie & Fitch (Phillipson) Featherweight loves the Cortland line though; roll casts are a dream!

This is all super helpful and covers a variety of situations. I’m looking specifically for a line to match a 6wt Fenwick Fenglass for catching creek bass in Central Texas. My gut says that a simple 6wt WF line would suffice, but would love input from the group (without having to start a new thread).

Fire away!

I like premium lines that are on clearance. Currently I am using a now discontinued SA sharkwave WF-6 on my FF806 and it seems to be really nice, it does have a little hiss to it, which I don’t mind. For my FF807 I have an Airflo Super-dri Elite WF-7, really nice line. The older Airflo lines have been a bit too stiff or have memory, this one is supple and floats really well.