Both have pro's and con's and at the end of the day it is down to personal choice and the type of biking you take part in.
jackets or trousers ) are very hard wearing and with a bit of care will last years and years. It offers fantastic protection when used with the proper "CE" protectors. If you have found yourself sliding down the road after some idiot in a car has decided to knock you off then leather will give you very good abrasive protection. The main drawback with leather is that it can be cold and is not waterproof.
To be able to do it's job properly leather needs to be quite tight to the skin so leaving not much room for warming layers. If you get caught out in a rain storm and your leathers get wet then your going to be cold and wet all day. They will also take a day or three to dry out. There are coatings that can be applied to them but at best they only really offer "resistance" to rain, not proofing.
Modern day textiles such as "Cordura" offer both good abrasive protection when used with the proper "CE" protectors and fantastic cold and wet protection. Many types of jacket and pant combinations are on offer today. Short or long jackets, some with removable liners, adjustable straps on the sleeves and waist, internal and external pockets etc etc. Most but not all also have built into the fabrics reflective piping and strips.
Pants also come with fixed or removable liners and armour in the knee areas.
Again textile or leather. Textile gloves usually have leather fitted on the palm, finger and thumb areas. They offer the same sort of protection as other textile clothing (i.e. against wet/cold). Leather gloves come in various colours and styles, but again as a rule are not water proof (unless stated). Both types come with varieties of knuckle protectors (carbon / rubber etc...), kevlar palms etc etc. Once again it's down to you and the type of biking you do. What ever you decide to get you need to be comfortable and need to be able to operate the controls of your machine, and remember if there's one part of you that WILL get cold....it's your hands.
Specific bike boots are a very important part of your biking kit. Many folk think that their every day shoes or boots will be OK.... WRONG !
Slow motion film footage of actual bike crashes, falls and slides show that the feet are very vulnerable, and tend to flail around when sliding down the road.
Shoes and trainers are nearly always torn off the feet on first impact with the road surface. Work boots with steel toe-caps are no better. The soles of the boots are usually very flexible and in some cases the toe caps have been known to amputate the wearers toes.
There's also the question of crush protection.
Imagine if the bike was on top of you. Take a pair of your best trainers and try to crush them side ways, from side to side........see what I mean ?
So a good pair of Leather BIKE boots with all the shin, foot, ankle protection built in are a must. A good bike boot will give you shin and ankle protection, usually in the form of CE armour built into the boot. The sole will usually have a steel or carbon fibre shank inside it to stop the foot from bending (the wrong way) and also will give very good side ways crush protection. When riding your bike the feet are very low down to the ground and don't really do a lot, so they get cold and wet.
- "Race" type boots are almost impossible to walk any distance in but do offer the best protection.
- A good "Touring" type boot will give you the protection you need (,i.e. shin crush etc) but give the added advantage of being a lot more comfortable for all day wear and are usually water-proof. Again like the gloves you need to be able to operate the controls of your machine.
- "Moto X" boots might look the dogs but if you can't change gear on your fireblade when wearing them, then they are no good for you.
the most important thing about bike kit is this
WEAR IT - EVERY TIME YOU GET ON THE BIKE !