There are so many options available in my local tackle shop I don't really know where to begin. I can understand which colour lead I should be using, the best match to the lake bed I am fishing over but the weight and shape does still confuse me.
I pretty much only have flat pear leads in my tackle bag in a couple of different colours and all weigh around 2.5 ounces. I find these work well for most of the type of carp fishing I am doing.
I usually have a simple bolt rig in a PVA bag with some pellets and this type of lead fits in easily. The fact it has flat sides means it does not slide or roll when fishing on slopes where as a rounded lead could drag your hookbait and also ruin the presentation. When a fish takes the bait I think there is also a good amount of resistance due to the shape and a good chance of hooking the carp. They are a nice compact lead and I can cast them far enough for the range I am wanting to fish. I normally buy the Korda leads but honestly they all look at the same to me.
I am currently fishing on a large syndicate lake and need to fish at range so I use the distance leads. They are more aerodynamically shaped to make casting at long range much easier. The further I need to cast the heavier the lead I buy. I do also have a selections of pear leads which I use for PVA bags and short range fishing. I will normally pick up several different shapes, sizes and colours at carp shows or online otherwise the cost is far too high. I think the key is to not over complicate and over think things like this and just buy a selection and try them out.