I have been through quite a few settings, including 4 halo's. The only advice I can give you is to make sure that you know what you are looking for in a halo prior to purchasing. There are so many types of halos...fine melee, bezel set, airline, no airline, etc...I kept switching mine bc I am lucky that my jeweler carries many stock settings and lets me upgrade, but it took me 4 tries to get it right so I didn't have to learn to love it or regret it. What exactly is your situation?
I had a very pretty split shank halo with a one carat diamond. I did have some regrets after I bought it. It just seemed so big and blingy. Not in keeping with my lifestyle at all. I sold it and immediately regretted it. I then went back to a solitaire which seemed too understated to me. I now have a beautiful halo with a plain shank. That works perfectly for me. It is a compromise and I am very happy with it.
I bought my first halo setting in 2004 and I haven't tired of it yet. I have a few of them, some with diamond center and some sim stones. You can always mount a colored gem in it later if you decide to go with a solitaire for the diamond. I attached a Beverly K. It's round but I just wanted to show something with a colored stone.
You might like a fishtail type ring, of you want to square the corners and slightly magnify the diamond. This one I attached is a Gordon Clarke.
eta: No matter what style, you'll find people here on PS that have changed rings a half dozen times before they got it "right." I'm not that way. I am very decisive, and I study before I buy, and I went to stores and tried on different mountings that stores had in stock, I played with the mountings at remount events, I had my jeweler order a couple of Stuller mountings before I decided which one to buy, I tried on colored gem rings to get an idea of what proportions and styles of settings worked on my hand. Do your research before you buy, The fishtail solitaire with either baguettes or small RBs as sidestones had a good long run in the '40s-'50s, and part of the reason for that is because it's an easy and comfortable style to wear.
Do a lot of research before you sink money into anything. And don't forget that the ring has to be comfortable to wear for long periods of time.
Thanks for posting this - I've been wondering the same thing a lot lately. I found a setting locally that's a shared-prong halo with a plain band and I keep thinking of having my cushion reset from the current four prong solitaire, but then I wonder if I will regret it. The price is reasonable and the jeweler has a good reputation, so I'm mostly worried that I'll regret having it done and wish I'd used the money to save toward an upgrade.
There are many different types and variations of halos so it is important to see each type and decide which one is right for you. I own several halo rings but none are the same. No regrets whatsoever.
I do not regret the halo exactly, but realized it is not suitable for daily use- the center stone is large for my small fingers....the whole ring is just too large and high because I work with babies. I would like a smaller ring for every day use. hope this helps.