It depends on how long you want to rear face for
. Just over a stone at 7 months sounds about average so I suppose any seat could work. You have the option of a group 0+/1 car seat, which typically rear face and harness until about four, or whenever DC reaches 18kg. These tend to be isofix and you can get ones that spin so make it easier to get DC in and out. Do you have a budget?
Good seatbelt ones are:
Joie Tilt
Joie Steadi
Britax first class—however this only RF until 13kg so the same as an infant carrier then is FF to 18kg
Maxi Cosi opal—again the same as the Britax first class
Joie stages—rear faces to 18kg and booster till 25KG. However doesn’t get the best safety results in forward facing so you would have to rear face then go straight to booster.
With seatbelt fitted ones, in rear facing the seatbelt can “block” entry, which some find problematic.
Isofix seats are:
Joie 360 spin
Joie 360 i-spin
Joie spin safe (doesn’t forward face, Swedish plus tested)
Joie i-spin sage (again, doesn’t forward face. Swedish plus tested and i-size
Britax dualfix
Cybex Sirona
Nuna norr (i-size and swedish plus test so doesn’t FF)
Nuna rebel
Maxi Cosi axissfix (however only RF to age 2)
GB vaya
Britax max-fix
Joie stages ISOFIX
BeSafe izi-twist
BeSafe izi-turn (RF only)
Maxi Cosi, Joie and BeSafe all do also sell seats which require an isofix base, and you can actually move these easier between cars, as you leave the base installed in each car and then the seat clicks onto the base (much like an isofix infant carrier), which some people can find useful for moving between cars. Although isofix can be easier to install I didn’t find it that easier to move the whole seat into different cars so used a spare when possible 
25KG seats are fitted with a seatbelt, however these do not block entry due to a different belt path.
Britax Two Way elite
Axkid move
Britax High way
Britax MaxWay
Britax multi-tech
Axkid MiniKid
These are all rear facing, although two way elite and the multi tech have the option to forward face with a harness to 18kg and as a booster from 18kg-25KG.
There are also forward facing options until 25KG however if you were to go with one of these, rear face as long as possible in the infant carrier. Ones are:
Joie bold. Requires isofix, top tether and seatbelt. Very secure. Difficult to move between cars. Will definitely be able to use until 12.
Cosy n safe Excalibur. Slightly shorter shell so may not last as long. Harness to 25KG again. Requires top tether
Maxi Cosi Beryl. Rear facing till 13kg, forward facing until 25KG.
Diono radian 5. Rear and forward facing until 25KG. Requires top tether in forward facing, and quite a few children outgrow height wise at around 6 as it’s shorter.
After an 18kg seat you can continue to harness in a 25KG seat or move to a booster if you feel comfortable doing so. Boosters are less of a minefield, and can be as little as £30. 