My experiences...
Craddock - Good, but recently slow (Covid-related?)
Paddock - Were OK, but stitched me up on their loyalty points scheme. I had cancelled an order and reordered stuff when I realised I had the wrong parts on an order, but they screwed up the points but just seemed unwilling to rectify it. Carp customer service. Probably OK if you don't have any problems on orders, but appalling if you need them to fix something. I'm boycotting them, now. Maybe I'm being petty, but it was not an insignificant sum.
LR Direct - my favourite. Very easy to add items assuming you know the part number, and easy to pick your manufacturer of choice. Quick delivery for most stocked parts, and the web site tells you if they need to order from a third party (Bearmach, for example) which will slow down delivery. Good prices, too.
Brit Car - useful for some items
eBay - excellent for 'one off' items where you'd otherwise incur a high delivery charge from the main suppliers,
https://www.lrworkshop.com/ is an excellent resource for checking part numbers and finding who can supply items, along with their prices. Has been very useful, although I generally defaulted to LR Direct for most items when I just knew what parts I needed.