You chose interior, change colour and hide the wood grain.
Primer followed by paint is the best solution here, but if using on wood that has knots or other surface imperfections, I'd recommend using a "knot blocking", shellac based primer as it will stop the discolouration of the knots bleeding through the paint in future, and will give a more consistent finish over wood.
Knot blocking/Stain blocking Primers
Zinsser BIN 500ml https://geni.us/xRsz 1l https://geni.us/ZAXsK or https://geni.us/PLQlxa 2.5l https://geni.us/MBJR Coo-Var Shellac Prime Stain Blocker 250ml https://geni.us/PDhqUxp Ronseal Knot Block Primer 250ml https://geni.us/5gMow 750ml https://geni.us/auDY 2.5l https://geni.us/OSMPWRp (Amazon Affiliate Links)
If you have a good consistent surface without the knots and imperfections that you get in real wood (bare MDF would be a good example) then ordinary primer will be absolutely fine, and you have the choice of water/acrylic based (dries quickly, less smelly, easy clean up and excellent colour retention but may not be quite as hardwearing and coverage is not as good as oil based) or oil based (takes longer to dry, can be smelly, clean up requires paint cleaning spirits, white paints may yellow over time, but coverage and durability is better).
Water/acrylic based primers
Leyland Acrylic Primer 750ml https://geni.us/Cn1De 2.5l https://geni.us/Ar4Zm 5l https://geni.us/YiRYtA Dulux Primer & Undercoat (various sizes) https://geni.us/rjrej4 Johnstone's Primer 750ml https://geni.us/RTZRWv 1.25l https://geni.us/yLx6XL Rustin's Primer & Undercoat 250ml https://geni.us/hkbVRLY 500ml https://amzn.to/3dtmfek 1l https://geni.us/5eC8qK (Amazon Affiliate Links)
There are many primers and sealer products which claim to be designed specifically for use on MDF - they may provide slightly better performance on MDF edge grain but in my experience they are not necessary - normal acrylic based primers work great. But these are a good option if you would prefer a clear product rather than pigmented.
Rustins MDF Clear Sealer 250ml https://geni.us/UG0EXI 500ml https://geni.us/Amthj 1l https://geni.us/rPCF 2.5l https://geni.us/Az7eHDe (Amazon Affiliate Links)
There are also some pigmented MDF sealers...
Leyland MDF Sealer White 750ml https://geni.us/l4bgEY 2.5l https://geni.us/NLs5EL Blackfriar's 250ml https://geni.us/qNSZj60 500ml https://geni.us/iHSX06C (Amazon Affiliate Links)
Spray Primers
Rustoleum 400ml https://geni.us/711A Plasti-kote 400ml Primer https://geni.us/WzYt7XD Motip Primer https://geni.us/kWrqSUp 151 Primer 400ml x3 https://geni.us/ETNsKpN Hycote Primer x4 https://geni.us/SOeA (Amazon Affiliate Links)
Paint
There are so many different paint types and colours to choose from so it would be difficult to list them here, and as I'm not a paint expert, I can't give too many recommendations.
But again, you have the choice of water/acrylic based (dries quickly, less smelly, easy clean up and excellent colour retention but may not be quite as hardwearing and coverage is not as good as oil based) or oil based (takes longer to dry, can be smelly, clean up requires paint cleaning spirits, white paints may yellow over time, but coverage and durability is better).
However, for a hardwearing option I would recommend eggshell, which has a subtle sheen to it but is very durable.
Leyland Hardwearing Acrylic Eggshell (White) 2.5l https://geni.us/mQCZbVv Dulux Eggshell (various sizes and colours) https://geni.us/pPRCG (various sizes and colours) https://geni.us/1fb20H Crown Eggshell (white) 750ml https://geni.us/eV2FvA (Amazon Affiliate Links)
Other paints are available in matt (no sheen), satin (subtle sheen) or gloss (high sheen). If using on real wood, always make sure that the paint you choose is appropriate for solid wood as it expands and contracts with seasonal humidity changes, so the paint needs to be flexible to accommodate that movement.
