Gas is the best to cook with for me. If they aren't lighting, it may be clogged up with dried food or a spill . Clean the top, make sure you soak what parts you can take off and let dry. I use Dawn for grease to soak my parts in. If it is only one burner, sometimes the part gets moved that has the opening for the igniton spark. If this doesnt work then you may be stuck getting a repairman... I have had this problem but it wound up being "operator error"..lol..me.. My dad worked for Lone Star gas co for his whole life. The flames may have something to do with the gas you are using..
I would surmise that there is grease as Pam said in the burner area. Most sealed tops can be taken apart by simply turning them which releases them from the top. Still others are removed by lifting the top of the stove that provides access to all of the burners and pipes. Normally there is one screw that holds each burner down. Remove it, lift the burner up and out. Soak in a hot sudsy bucket, clean all the holes using a toothpick. Rinse and put burner back after its dry. That usually does the trick.
What has happened is grease has filled the tiny opening that allows the gas to flow to the pilot light. Once cleaned out, it will work fine again.
I have a burner that has never really lit i just use a clicker to light it.
You might need to replace the ignighter. Go to the web site of the manufacturer of your stove and see what info they give. I have replaced mine in the past, not hard to find them.
Take the burners to where they air tires or have an air compressor. Connect the airt to the burner, force air though the burners. This should clear out any thing that s blocking the burners. I have done this many times before.
If it's clogged soak the burner in a solution of powdered Cascade dishwashing soap and water, only powder, liquid won't work to get the grease out. Soak for a15-20 minutes.