your opinion on subwoofers in two channel

If you are using monitors as speakers, adding a sub is a must in my opinion. You would get a bigger soundstage and more weight and body with instruments and voices. A sub adds the bottom frequency which in turn helps your middle and upper frequency sound more natural.
I added a sub when I had JM Lab Mini Utopia and could never turn back without a sub. Have fun.
Nickk

Depends on your two channel audio objectives, for each objective my suggestions are;

Balance of esthetics, quailty & function: get small moderately priced speakers (6" woofers or less, 6 db at 60 to 100 Hz) and a reasonably priced mid-size sub (8" to 10" woofer to cover 30 to 100 Hz). Great sound and looks good.

Pure high end audio: spend your money to upgrade to large expensive accurate LF range speakers (12 or 15" woofers, 6 db generally between 30 and 50 Hz) before ever considering a sub to complement the extreme low end (12 to 15" woofer at least to cover 20 to 50 Hz). Incrementally better sound than above with the drawback of big imposing boxes and significantly higher cost.

interesting thoughts and knowledge thanks i understand what both of you are saying...thanks

I think good subs that can be tweaked in to mate with your room & system do make sense and can add to the enjoyment in a meaningful way. Less adjustable subs or trying to do to much from a single sub can be more of a distraction than a benefit. And it depends on your taste in music. If there is little to be heard then a sub adds little (duhh, ok so that ain't such an epiphany).
To answer your question directly, if I had to choose between better sound overall or adding a sub, I'd take the former, but if I could afford the additional extravagence of one or two good subs I'd go for it. IMHO, YMMV, DEYS.

Can be a good thing if you like the sound of your system for 2 channel music and just wish it had more sub bass. You can enhance the lows without messing up the rest of the system. Also if you don't have the room for large floor standing speakers.

If the smaller speakers have great mids and highs, a really good sub can make them sound like larger speakers costing much more than the cost of the 2 speakers and the sub if you can get them to integrate well. REL subs are pretty easy to integrate.

Back in the 90's a lot of people would match two of the small B&W Matrix 805 speakers with the Matrix 800 sub. It would come close to the performance of the Matrix 801s for those with smaller rooms and/or those who could not afford the M801s. A pair of M805 plus the Matrix sub was about half the cost of the M801s. Probably is still the case with the current B&W 805s and subs.