I’ll assume that you are in the US.
While one cannot make a hard and fast rule, generally, going to a bigger church or a more liberal one is going to be easier on you.
For example, in the US, the ELCA (Evangelical Lutheran Church of America) seems to be rather non-in-your-face-preachy. It is somewhat liturgical, but should be low-key and casual enough that you won’t be embarrassed to not know what to say.
Episcopalians also are also non-threatening, but they can also be quite liturgical and formal so you might feel out of place not knowing what the proper congregational responses are, but they aren’t hard to learn.
Other Protestant churches on the more liberal end are going to be less likely to be in-your-face bible thumping “accept Jesus!” “are you Saved” type places. Though, of course, every congregation is different so these are just general rules. Other liberal churches in the US include the United Church of Christ, the Disciples of Christ, Presbyterian Church USA (perhaps more middlin’), and the United Methodist Church.
Churches that you may be less comfortable in include Southern Baptists, Independent Fundamental Baptists, Pentecostal groups, Mennonite groups, Seventh Day Adventists, Schismatic Anglicans/CANA, Calvary Chapel, and any church that calls itself “____ Bible Church”.
In terms of size, going to a church with a large number of attenders is going to make you fade into the background to some degree. In those churches, sometimes getting attention when you want it can be a challenge.