The best waterproofs on the motorcycle are...

Exhibit A
I know a chap I will call SC for the purpose of this post. In a sense, SC has always been locked in a battle with nature. I've known him for about seven years now, the SC's battle for the perfect rainproof gear still goes on.

Exhibit B
I know of a chap who knows a chap (really) who rides around wearing an O'Neill wet suit (you know the surfing type one) because it is the most waterproof kit he can find. Does preclude wearing much else though...

Exhibit C
MB lives in the UK most of the time. According to him, no matter how expensive the rain kit he purchases, by the end of one year (in UK time, one year is actually almost a full year of rainy weather), it's finished.

After watching these three struggle with rain kit, here's my solution. First of all, no wetsuits. That's way too extreme, even for me. Second, expensive rain kit is good only in that it will allow less water in through the collar/cuff etc. I am yet to read about or see genuinely perfect rain kit. Although, truth be told, I do own a Blue Delta winter motorcycle jacket that is actually fully perfect. But I am talking about wear on top of riding kit kind of waterproofs, not membrane equipped kit.

I used to own a Japanese rain coat once, and that split at the seams almost precisely a year later. I've owned expensive nylong rain suits that were coated to waterproofness. The coating eroded in a year. Same result. So here are my suggestions for buying rain suits for motorcycling

1. Buy plastic
   Yes, really. By plastic I mean material that is already waterproof. Not something that needs treatment to become waterproof. PVC is great. It's sweaty, but so are all rainsuits without exception
   
   
2. Buy cheap
   My current upper limit for a rain suit is Rs 350. That's about enough for a year's worth of utility. In any case, filthy they will become in time, and it's just easier to throw a battered old one away and start the season with a fresh suit. I wear a Prince Luxor, usually purchased from Glory in Four Bungalows Market, Andheri (w), Mumbai
   
   
3. Check the cuff and collar areas
   If the jacket zips so that you can zip the collar into a vertical tube, that's the best. Cuffs should have really tight elastic. It makes it a bitch to get on by the road side, but then it won't slide up or leak
   
   
4. Buy light
   Don't be tempted to buy dark colours. They may mask the grime that accumulates, but riding at night, you are nigh invisible to other road users. Which doesn't affect them much, since they are wearing 2-ton metal suits with crumple zones.
   
   
5. Buy gloves and rain overboots if you can
   Being dry while wearing squelching boots and soaking wet, floppy leather gloves is almost as bad as a wet crotch. So spend some money. Nothing available in India, unfortunately, but Joe Rocket Ballistic waterproof gloves, and waterproof overshoe are very helpful. Unfortunately, the latter are coated nylon. So be gentle while putting them on, or the coating will rip. A great alternative is a DMS boot (remember to buy the ones with the uncut 'tongue' they are ankle deep waterproof for than an hour, until the leather soaks through and the water begins to weep in).
   
   
6. Get tightening straps made
   Now firmly in OCD territory, get four simple straps made. Each has to be a length of nylon, long enough to circle your forearm (two of them) and you calf muscle (the other two). They need to have the soft part of velcro at one end, followed by the rough part and a plastic D-ring, or square ring at the other. Use these as hook and look closures to secure your rain suit at the you forearm, below elbow and calf, a little below the knee. If you wear armoured kit, the straps will not only hold the armour in place in a crash (tried and tested), they will also create a second barrier for any water trying to get in.
   
   
7. Wear the glove under the cuff
   Normally, I wear the glove so that the gauntlet goes over the jacket cuff. But in the rain, especially in traffic (slow speeds), the water runs down the forearm and into the glove. Very annoying if you wearing a waterproof pair (water can't get out, takes forever and a half to dry out). So wear the glove under the cuff and tighten the cuff as much as you can.
   
   
8. It's only water
   At the end of the day, it is only water. So don't think about it too much. Wet crotches only feel so bad because you choose to focus on it so much. Think positive, it makes the rains a heck of a lot easier to live with.