which board to buy altera FPGA

Hello
I am a bit confused on which FPGA board should i be buying for research and learning purposes
I have found the
DE1-SoC board from altera to contain a lot of advanced technologies + a dual core arm processor at a reasonable price of 190$
https://www.terasic.com.tw/cgi-bin/page/archive.pl?Language=English&CategoryNo=167&No=836&PartNo=2

and the DE2i-150 which is a great board with an intel hyper threading processor that expands the learning to a more interesting field in using intel processors and hardware this one costs a lot at about 600$
https://www.terasic.com.tw/cgi-bin/page/archive.pl?Language=English&CategoryNo=139&No=529&PartNo=2

i have also taken a look at this board the DE2-115 which is great and contains all educational needs but a bit lower end than the other at a 595$
which is still expensive a bit
https://www.terasic.com.tw/cgi-bin/page/archive.pl?Language=English&CategoryNo=139&No=502

so which one do you think is the most advanced and in which you can use to accomplish higher levels of learning and design ?

What is your level of proficiency in logic design?

masters degree in computer engineering and hardware design i have worked on a thesis "improving the odd-even sorting algorithm using bitwise comparison on FPGA", some basic FPGA projects (mini-mips processor, alu, shifters...) and a USB to pc project on pic18f4550 and a couple more pic projects

The two important questions are:
1. What do you want to do with it?
2. What is your budget?

most probably research for implementing IEEE papers in image processing/signal processing and mastering all important hardware protocols i was thinking about getting the DE1-SoC board because of it's reasonable price but the ARM processor is hardware implemented in the FPGA and will cut down it's size + if i want to write my own IPs for the ethernet, usb and communication protocols i will be obliged to do that in C
i was looking to designing my own mini processor and operating system on FPGA from scratch

What is your level of proficiency in HDL ?

hmm beginner-intermediate i guess my thesis was written in VHDL