Lenovo Thinkvision product line has nice thin borders, IPS panels, reasonably priced. Various sizes and resolutions available. Colors are competitively good at that price point, relatively neutral and adjustable. They have extra ports too. I've got two of those as side-wing monitors, P24h and q models (24").
The middle panel is an LG Ultrafine 5k. Not cheap but it's (for now) the best option as a true retina display as an external monitor, other than the outrageously expensive 6k XDR from Apple. Other LG Ultrafine displays are also worth checking, they are expensive but have good color accuracy.
Whatever you take, I'd say that WQHD (2560x1440) is the minimum resolution for 24" and UHD (3840x2160) for 27". Otherwise the text will be quite blurry, not very nice to read, compared to the internal panel. IPS panels are generally quite good. Gaming monitors often have poor or exaggerated colors, avoid those.
The two P24 monitors are powered by DisplayLink, if you ask how to connect more than one external display. Various threads about that in this forum, also YouTube videos. Works fine for me, even for graphics-intensive work. Zero lag or quality issues. Without this it's only possible to add one external monitor to M1 Air.
It's a bit of a hack, but using
BetterDummy can greatly improve the font quality for lower resolution external displays, because it enables 2x rendering of the image, first upscaling in memory to double resolution, then downscaled to the panel. Better sub-pixel rendering for fonts.
