Sorry for the long post below, this thread really struck a chord... so just wanna share my manual portrait lens journey...
Like you, I started looking at manual portrait lens, not satisfied with the kit 18-55. I started with the CCTV 35mm F1.7.
Being a newbie, it was not easy to work with manual lenses at first, but once I got into it, every sharp image became something satisfying, and pics tt can never be taken with the 18-55 materialized... but the CCTV 35mm had a downside .. wide open, it tends to vignette... there's a 'dark shadow' around the edge of the pics... kinda like a lomo effect, but not really desirable if you dun want this effect.
So I went into old SLR lenses.. the first I got was a 50mm F1.4 Minolta MD that I bought fr someone here..
I was shocked at the size of the adapter + lens package, something I had to live with.. but the pics quality was great with the fast lens ! however, another downside with the MD F1.4 is the softness when wide open (at F1.4)... there is this 'dreamy effect' around subjects, so not entirely sharp... but stopped down a few stops, and it is dead sharp (but most lens are like this, with exceptions below)
Well, I didn like the size, so I decided to go into pancakes. The first classic pancake I got for myself was the Konica Hexanon 40mm F1.8.
This was a wonderful lense, compact, smooth mechanism (with a nice 'click' sound when focus ring turned all the way), relatively sharper than the MD ... but.... as similar to all SLR lenses, the adapter is huge, so I still had a big package I didnt really like...
So I went thru a series of lenses, in my quest for sharpness and compactness... Olympus OM 50mm F1.8 (loved the color/contrast, but sold, cuz I already had my MD F1.4), Canon FD 28mm F2.8 (wanted to try 28mm, but sold this away cuz got my contax biogon), Konica Hexanon 50mm F1.7 (read that it was sharp, but in actual fact not as sharp as I wanted, so sold away)...
Finally, I found the most compact lens I had to date: the 1960-era Olympus 'Pen F' 38mm F1.8:
Short adapter, short lens, relatively fast at F1.8, easy to use 38mm range, and simply its Vintage quality made it a keeper... I still shoot with it very often.. super loved it... but it still had certain downsides:
a) still slightly (though less than my MD 1.4) soft wide open
b) no multi-coating (1960s mah), so can get quite a bit of internal reflections when shooting at light
So finally laid my hands on the lenses that are always on my camera now - the Contax G Carl Zeiss series
Super sharp wide open (both the 28mm F2.8 and 45mm F2), only slightly bigger than my oly pen f, the pair I got were simply my favourite lens to date. However again, they are not without downsides:
a) expensive ($500 upwards)
b) short focus throw (not really that smooth to focus, as they are autofocus RF lens, not SLR lens made for manual focusing)
So well, it is up to you to try out different lenses and decide what you want.. think what Anthony Lee said is very true :
Just go ahead and pick any 50f1.8, the cheapest possible with the cheapest adapter and shoot. Very soon you will outgrow what you have and your real problem will begin. I have been doing this for a few decades and still never learn.