You’ll be happy in either place. Medical care in Thailand is better than Bali, but both have very modern medical facilities that cater heavily to expats and medical tourists, so nothing to worry about for your basic needs in either place unless you go far off grid. Pharmacies are plentiful in both, always with the caveat that fake drugs do exist and are an issue throughout Asia.
Internet is certainly better in Thailand as well. It’s plentiful in both places, just where a cafe in Bali has a unstable 1Mbps connection, cafes in Thailand have reliable 3-10Mbps connections.
Often in Bali I get frustrated at cafes end up using 3G because it’s more reliable, but then I’ll occasionally do that in Thailand too.