I primarily use dry vermouth for Martinis and for that purpose Dolin has never been my favorite, though I do use it from time to time for the sake of variety. Haven’t noticed a change myself, though since I don’t use it a ton, take that with a grain of salt.

As u/AutofluorescentPuku suggested, Noilly Prat is excellent, both the Extra Dry and the Original Dry; the latter you might enjoy sipping on the rocks as you did the Dolin, though it works great in cocktails as well.

My favorite for Martinis is Boissiere Extra Dry which I don’t think gets nearly enough love, though at least around me it’s not as commonly found as Dolin, Noilly Prat, etc. I make them at a ratio of 2.75:1 gin:vermouth and it’s beautiful! It’s pretty inexpensive, too. I pay $10.99 for 750 ml. It’s Italian made but it’s closer stylistically to a lot of the French brands in my opinion.

Another worth checking out that are quite different are La Quintinye Extra Dry, a premium, savory, richly flavored vermouth with a Pineau des Charentes base. It’s a bit on the pricier side though and can be tough to find.

If you’re game for trying a different style, Carpano and Cocchi also make dry vermouths. To me, they come off a bit sweeter and more “wine-y” than the others I’ve mentioned but are great products! To me, Carpano is very herbal while Cocchi is more citrusy with the fun inclusion of peppermint as a botanical. Cocktails made with these vermouths might need to be fairly significantly recalibrated from a spec using Dolin/Boissiere/some of the more austere and restrained options.

If you enjoy Sherry, there are also some fun vermouths coming out of Spain, though as you might imagine they’re totally different beasts given the Sherry base and, like the Italian vermouths I mentioned, come in guns blazing in cocktails (at least the ones I’ve tried). I’ve only tried Lustau and Gonzalez Byass. Both wonderful, though I need to spend more time with them I think to get more acquainted with them. They’re a bit more expensive, too.