AVR32 vs PIC32 which has better support, learning curve

which of the two AVR32 or PIC32 is easier to program, learn and which has more firmware, software, source code available? i see more avr32 source code via atmel studio and ASF and documentation(schematics) than pic32. is this right? specifically usb based MCU seems better supported by avr32 than pic32, there is also issue of licensing of source code. i am a beginner so i might be wrong.

PIC32 or AVR32? STM32!

The PIC32 is made by Microchip and the AVR32 was made by Atmel that was bought by Microchip. Both have free GCC-based compilers available for them (and the rest of the toolchain as well) so I'm not sure about licensing of the source code.
The PIC32 is based on the MIPS technology (which is different from the other PIC families) whereas the AVR32 is based on their own processor design that is an extension of their 8-bit and 16-bit technologies. However, much of this is hidden by the compiler (although you will need to read the respective compiler documentation for details of how to handle things like interrupts etc.).
I'm not sure what you mean by either device providing better support for USB. Ultimately both MCUs just provide the hardware and there needs to be firmware written to make sue of it - therefore it comes down to the availability of libraries and they are available for both devices.
Also the choice of device can also depend on what you need to achieve. Do things such as footprint, memory (RAM and FLASH) size, peripheral type and number, CPU clock speeds, voltage and power consumption and device cost matter?
Also I also like the STM32 and Cypress PSOC range of devices (which are ARM based devices). It all comes down to the appropriate device for the purpose.
Just my opinion...
Susan

If you're a beginner and would like to use 32-bit MCU, I'd recommend ARM Cortex-M microcontrollers. A lot of documentation, sample code, manufacturers etc. Atmel (that is a part of Microchip now) has its Cortex-M series (xplain boards), STM32 is also good (Discovery boards, NUCLEO are perfect to start).
As for licensing, vendors usually provide low-level libraries with small restrictions, like ASF for Atmel, HAL for ST (save licence in the source, use the code only with vendor MCU etc), so it's not a problem.

isn't arm cortex M microcontrollers are difficult to learn for beginners. I have opted for PIC32. trying to learn usb with pic32.

I suppose it all depends on what you mean by "...difficult to learn...". All microcontrollers have their own special "quirks" and you need to be familiar with them. Some of the basics will follow you from one type of device to another (i.e. the basic thinking about how to design embedded apps, what interrupts are etc.) but there are some things that you just have to learn about whichever device you select.
Also see my previous comment about how programming in C will help distance you from some of the peculiarities of a specific device.
Personally, I'd be looking more at which device fits my needs better. If I'm just learning about a device then I'd get a development board which typically have a number of peripherals on them for practice purposes. I also download the various development tools that the manufacturer makes available and start right back at the 'flash a LED' app so that I learn how to do the basics of programming (e.g. the configuration settings for PIC devices are critical but often overlooked - get those wrong and you can waste a LOT of time at the start; get them sorted and life is MUCH easier - the same is not necessarily true for PSOC or other families if devices where the IDE can hide these from you to some extent).
If you have a specific project in mind then factors such as power consumption, peripherals, possible unit cost and support components, footprint and memory become important. They can all add to the learning curve butin very different ways.
Susan

An advice which worked for me was:
Find a controller for which a friend or acquaintance (who is willing to help you) is familiar with.

Online forums are great, but nothing beats a person to person discussion.

This advice works for any hobby or trade: carpentry, auto repair, machine shops, etc.